HR: 16:40h
AN: A44B-03    [Abstracts]
TI: Adsorption and Uptake of Acetone on Ice Studied with Ambient Pressure Photoemission Spectroscopy
AU: * Bluhm, H
EM: hbluhm@lbl.gov
AF: Lawrence Berkeley Laboratory, Chemical Sciences Division, MS6R2100, Berkeley, CA 97420, United States
AU: Ammann, M
EM: markus.ammann@psi.ch
AF: Paul Scherrer Institute, PSI, Villigen, 5232, Switzerland
AU: Starr, D E
EM: dstarr@bnl.gov
AF: Lawrence Berkeley Laboratory, Chemical Sciences Division, MS6R2100, Berkeley, CA 97420, United States
AB: The interaction between small molecules and ice particles has broad implications in atmospheric chemistry. However, the influence of adsorbed molecules on the thickness and properties of the liquid-like layer at the ice surface is still not fully understood. We have used a combination of synchrotron-based Ambient Pressure Photoemission Spectroscopy (APPES) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) to investigate the adsorption and uptake of acetone on the ice surface at temperatures of 215-245 K. The combination of APPES with NEXAFS allows one to directly correlate the amount of adsorbed acetone with the state of the ice surface, in particular the presence of a liquid-like layer. Uptake measurements using the integrated C1s peak area as a function of acetone partial pressure indicate an adsorption energy of approximately 45 kJ/mol. In addition, high resolution C1s spectra as well as O and C K-edge NEXAFS both show little to no modification of the acetone molecule or the ice surface upon adsorption. The combined results indicate a weak interaction between the acetone molecule and ice surface, and the absence of a liquid-like layer both for clean and acetone covered ice at temperatures between 215-245 K.
DE: 0738 Ice (1863)
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting